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Thread: Engine Starting/Tuning/Troubleshooting Discussion

  1. #21
    Interesting to read the debate on alpha-n vs. speed density.

    I'm sure that alpha-n is easier to tune for one engine hardware set, on one particular day.

    But, change anything that alters your air flow, and you have to re-tune. Or, if anything hardware-wise changes over time, your tune goes off.

    Speed density should be more 'robust' (in control terms) and more applicable to projects where multiple hardware sets are in use.

    Juat my opinion...

    Regards, Ian

  2. #22
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    You could always use alpha-n with a MAP compensation..

    Originally posted by murpia:
    Interesting to read the debate on alpha-n vs. speed density.

    I'm sure that alpha-n is easier to tune for one engine hardware set, on one particular day.

    But, change anything that alters your air flow, and you have to re-tune. Or, if anything hardware-wise changes over time, your tune goes off.

    Speed density should be more 'robust' (in control terms) and more applicable to projects where multiple hardware sets are in use.

    Juat my opinion...

    Regards, Ian

  3. #23
    -check injecotrs. Same as the spark. The thing to be sure about with the injectors is that the ECU may or may not have a setting for the injector impedance. More resistance = more draw.
    Isn't this backwards?

    V=IR --> I=V/R

    As resistance increases the current through the transistor is going to decrease. That is why you may see ballast resistors on low resistance (low impedance) injectors.

  4. #24
    Epic thread here.

    I'll add my thoughts:

    1. If you know how the wiring loom should be wired, and check it all once, it *will* work, first time. In 2010, 2011, and 2012, I checked our looms before first car engine crank, and they all caught/started up no problems. To be fair, we don't change a lot year to year. All I'm saying is: know what it *should* be, and check it once; no need for multiple checks. You gotta be 100% sure what you want though.

    2. Our dyno is a steady state only, so no pulls. We have speed control via PID, so it's set the RPM, and open the throttle to get to your mapping point

    3. Bosch LSU measure a current (or some black magic). Whether it's in LA or AFR or something else doesn't matter. We use lambda, cos that's what the textbooks here use, and as mentioned, it's easy to know what it means. LA 1.00 is stoich, LA < 1 is rich, etc

    4. We use MAP (not TPS). It's how I inherited it, but I like it cos you can't really mess it up. If you fiddle with either your TPS sensor, or the throttle body/butterfly, then doesn't your tuning do strange things? We use TPS for accel enrich though (way better than MAP we had to use on the M48)

    5. In 2011, we tried ET fuel compensation on the dyno, and it didn't work (at idle). We did end up using oil temp idle comp on the car at idle. This year, we using idle RPM targeting (ecu only - no throttle body stuff). Aiden Turner (Turns on here) is the guy to ask.

    6. We do play with inj timing on the dyno (only at WOT), and found it does make a diff. It's very fast to do a sweep at an RPM, so why not?

    7. We've never had a problem with cranking maps (and we run e85...) JUst extend the lowest tuned RPM back down to 0 RPM, and it works. I did this in 2010, and forgot that part of the map is used for cranking - had no effect on cranking...

    8. Blipping the throtte from idle - make sure the overrun cut is set right, or turned off.

    9. We use a water to water heat exchanger in the dyno - it cools too well, even though it's a tiny thing. We have cooling tower water in our dyno cell @ 20C and high pressure/flow. We actually run a bit cold on the dyno, even at max power for 10 minutes+. The oil temps on the other hand... (and we've got a dedicated EWP80 just for the oil cooler)

    10. We run a CBR600RR with stock lower injectors only on E85, and have had no injector duty cycle problems. Or maybe we're not looking carefully enough...
    Rex Chan
    MUR Motorsports (The University of Melbourne)
    2009 - 2012: Engine team and MoTeC Data acquisition+wiring+sensors
    2013 - 2014: Engine team alumni and FSAE-A/FStotal fb page admin/contributer

    r.chan|||murmotorsports.com
    rexnathanchan|||gmail.com
    0407684620

  5. #25
    Originally posted by atm92484:
    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
    -check injecotrs. Same as the spark. The thing to be sure about with the injectors is that the ECU may or may not have a setting for the injector impedance. More resistance = more draw.
    Isn't this backwards?

    V=IR --> I=V/R

    As resistance increases the current through the transistor is going to decrease. That is why you may see ballast resistors on low resistance (low impedance) injectors. </div></BLOCKQUOTE>


    Touche sir....must of been a friday night i wrote this or something changing it now
    South Dakota State University Alum
    Electrical/Daq/Engine/Drivetrain/Tire guy '09-'14

    Go big, Go blue, Go JACKS!

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